Having fun with Bitmaps in AS3
So, I wanted to grab a snapshot from my camera in Flash Player and send the image to the server to share it in a web conference.
Thanks to the excellent work of Tinic Uro of Adobe I started off with adding his AS3 port of a JPEG encoder to my app to make sure that it doesn't send megabytes data to my server. Have a look here for his article on the AS3 JPEGEncoder.
It turned out that my pc is a bit slow and will take about 8 seconds to encode a 640x480 bitmap. This wouldn't be so bad if Flash Player was multi-threaded, but as it is, the player (and the browser that runs it) will block during the encoding. On my newer laptop, the encoding only takes about 1 second. But hey, I'm probably not the only one that has an older PC, so I decided to do something about the blocking.
I modified the JPEGEncoder class so that it chops up the work in chunks and automatically adapts the chunksize to a maximum blocking delay that is configurable. It also emits ProgressEvent's and a complete event when done. And I threw in a cancel() function as well. Here's the source for JPEGEncoder with ProgressEvent.
With this modification, the encoder pauses for 10 ms about every 200ms to let the player do other things like updating the display list while only adding about 5% to the processing time. And I added a progress bar to show the user how the encoder is doing.
Have fun with it.
Thanks to the excellent work of Tinic Uro of Adobe I started off with adding his AS3 port of a JPEG encoder to my app to make sure that it doesn't send megabytes data to my server. Have a look here for his article on the AS3 JPEGEncoder.
It turned out that my pc is a bit slow and will take about 8 seconds to encode a 640x480 bitmap. This wouldn't be so bad if Flash Player was multi-threaded, but as it is, the player (and the browser that runs it) will block during the encoding. On my newer laptop, the encoding only takes about 1 second. But hey, I'm probably not the only one that has an older PC, so I decided to do something about the blocking.
I modified the JPEGEncoder class so that it chops up the work in chunks and automatically adapts the chunksize to a maximum blocking delay that is configurable. It also emits ProgressEvent's and a complete event when done. And I threw in a cancel() function as well. Here's the source for JPEGEncoder with ProgressEvent.
With this modification, the encoder pauses for 10 ms about every 200ms to let the player do other things like updating the display list while only adding about 5% to the processing time. And I added a progress bar to show the user how the encoder is doing.
Have fun with it.
posted by Sander Kruger at 21:38
5 Comments:
Hi Sander... I'm interested to using your fork from (progressive) jpeg encoding.
I already download the AS and make a trial, but nothing happens.
It always returns 607 bytes (jpeg header).
I currently have been using Flex 2.01.
Any trick about this ? What could be wrong ?
best regards
Henrique
Hi there,
I've been working with your AS file in a project of mine, exporting jpgs with any dimension set. The code you provided works beautifully up until a certain point. At that point, it just hangs. I've noticed it primarily on image sizes above 2000 pixels square. The event.bytesLoaded item still returns a value, but nothing comes out. One I just ran was 2100 x 2400 and the program crashed around 1272. It is rather confusing to me. Might you have any ideas?
there is 404 :(
the link to the source file is broken.
Yet 5 years later, and this has worked smoothly for me!
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